1. Field of the Invention
The present invention pertains to fiber optic connectors for optoelectronic devices or optical subassemblies. The invention more particularly concerns a fiber optic plug for connecting to a receptacle of a small format optoelectronic package such as a modular high density multiple optical transmitter/receiver array.
2. Discussion of the Background
Optoelectronic devices such as optical transceivers are known in the art and include active optical devices or diode packages. One such optoelectronic device is a removable optoelectronic module as described in U.S. Pat. No. 5,546,281, which is hereby incorporated herein by reference. One end of the removable optoelectronic module includes two SC style ports or receptacles forming an SC duplex receptacle for receiving SC style ferrules. Often, the two SC style ferrules are either ganged together or are assembled in a common plug body so as to form an SC duplex plug. The ferrule of an SC plug has a nominal diameter of approximately 2.5 mm. When the ferrules are incorporated into a single body or are ganged together, the center-to-center distance between the two ferrules is approximately 12.5 mm. As compared to conventional copper plugs, such as RJ-45 style plugs, the size or panel profile of the SC duplex plug is large.
In order to increase the number of ports which can occupy a panel, a reduced size ferrule and plug were developed and is disclosed in U.S. Pat. Nos. 5,481,634 and 6,102,581, both of which are hereby incorporated herein by reference and where such a plug is known as an LC plug connector. The ferrule of the LC plug has a nominal diameter of approximately 1.25 mm. When two LC ferrules are ganged together or are incorporated into a single body the center-to-center distance of the two ferrules is approximately 6.25 mm. Thus, the number of ports located in a given linear dimension using an LC duplex plug is equivalent to the number of copper ports located in the same linear dimension using the RJ-45 plug, since the size of the profiles of the two plugs are similar.
FIG. 1 shows a plan view of a panel showing the relative size of RJ-45 ports 2, SC ports 4, and LC ports 6. Twenty-four RJ-45 and LC ports 2, 6 are shown and only twelve SC ports 4 are shown occupying similar linear lengths. The increased port density allows more data to be moved through a given port profile of networking equipment. FIG. 1 is found in a document entitled xe2x80x9cEvaluating the LC SFF Interface for Single-Mode and Multimode Applicationxe2x80x9d and is available on the internet web-page at the home of the LC Alliance (www.lcalliance.com). The above-identified document is hereby incorporated herein by reference.
Other plug connectors have spacing between optical fibers which are nominally spaced center-to-center at approximately 0.75 mm. One such plug connector is known as the MT-RJ and is described in an article entitled xe2x80x9cPerformance Comparison of Small Form Factor Fiber Optic Connectorxe2x80x9d which is available on the internet web page of the LC alliance, and where the document is hereby incorporated herein by reference. The MT-RJ plug connector includes a body or single ferrule, where the body surrounds and holds two optical fibers. However, such plug connectors do not employ multiple ferrules and as a result the coupling of light into and out of a fiber in an MT-RJ or other multi-fiber single ferrule connector can not be independently optimized for each fiber. Therefore, optical plug connectors which do not incorporate a single ferrule for a single optical fiber introduce new problems, and, as such, optical plug connectors which do not incorporate a single ferrule in conjunction with a single optical fiber are not further considered.
Therefore, there is a need in the industry for an optical plug having multiple ferrules where a single ferrule is assigned to a single optical fiber and which increases the port density in a panel or device.
Therefore, it is an object of the present invention to provide an optical plug connector which increases the port density in a panel or device.
It is still another object of the invention to provide a plug which mates with a receptacle of a small format optoelectronic device.
Another object of the invention is to provide a plug which is economical to manufacture.
Yet another object of the invention is to provide a plug which incorporates standard parts and features.
In one form of the invention, the plug includes a body and ferrules attached to the body. Each ferrule has an aperture. Additionally, all of the ferrules exist in a plane and each ferrule has a diameter substantially equal to 1.25 mm. The aperture of each of the ferrules is separated from the aperture of an adjacent ferrule by a distance of 3.125 mm.
In another form of the invention, the plug includes a body and two ferrules attached to the body. Each ferrule has an aperture. The aperture of one ferrule is separated from the aperture of the second ferrule by a distance of 3.125 mm.
Thus, the device of the invention is superior to existing plugs. The plug of the invention increases port density in a panel or a device. Furthermore, the plug of the invention is easy to manufacture and incorporates features of commercially well received connectors. Thus, the device of the invention is smaller than prior art devices.